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1.
萧山-球川断裂是浙江地区1条大规模的北东向断裂,在该断裂附近曾发生过多次破坏性地震。本文通过地质调查、电法勘探和探槽开挖等方法,对萧山-球川断裂富阳—建德段第四纪活动性进行了研究。萧山-球川断裂富阳—建德段的遥感影像线性特征清楚,对地貌的控制作用较为明显,对山前的第四系发育有明显影响。通过对断裂露头剖面的分析,认为萧山-球川断裂富阳—建德段活动性质以走滑兼具逆冲为主。通过本次开挖的富阳峙山村探槽,结合ESR年龄测定,判定该断裂在第四纪早、中期有过活动,但未断错上覆中更新统上部地层,其最新活动时代为早、中更新世。  相似文献   

2.
板岩作为一种浅变质岩在我国有着广泛的分布,对其地震波速度的研究将有助于对这类过渡性岩石的有效区分,对于浅层地壳的各向异性研究也具有重要意义.本文对采自云南丙中洛地区的板岩样品进行了地震波速度的室内实验研究,其中部分实验是在加拿大Dalhousie High Pressure Laboratory完成.实验获得了板岩在围压10~600 MPa条件下、不同构造主方向(X,Y和Z)上的地震波速度,在围压600 MPa时,X、Y、Z三个方向的P波速度分别为6.58、6.46、5.91 km/s,平均速度为6.30 km/s,S波平均速度约为3.62 km/s,VP/VS=1.74;并初步分析了板岩地震波速度、横波分裂及其波速各向异性随着围压的变化规律,发现所测量的板岩在较低围压(<150 MPa)时波速的各向异性随围压升高而迅速减小,主要是由于其内部微裂隙的定向排列引起的,而随着围压的继续增加(>150 MPa时)微裂隙基本闭合,黑云母、阳起石等片状矿物的定向排列成为其地震波各向异性的主导诱因,此时(围压为600 MPa)VP、VS的各向异性分别稳定在13%、16%左右.本研究所获取的基础实验数据及所探讨的板岩地震波性质将为确定地壳上部显微裂隙的优选定向、浅层地壳的各向异性分析、地球物理模型条件约束等提供基础.  相似文献   

3.
In recent decades, increased extraction of groundwater for human and agriculture consumption has led to a substantial drop in groundwater level in large areas of across the world. Declining groundwater levels is a serious problem in itself and has multiple economic, social, cultural, political, security-related, and environmental externalities. The negative economic-environmental externalities of overextraction of groundwater in the Orzouiyeh plain in the Kerman Province, Iran, were evaluated using methods such as replacement cost, production function, market prices, shadow price, and the value of the input marginal product. After evaluating externalities, the Positive Mathematical Programming method was used to evaluate different water policies to reduce the consumption of groundwater. The total economic losses due to the externalities were calculated to equal 2.8 U.S. million dollars. The damages caused by environmental externalities were calculated to equal 436.1 U.S. million dollars. The results related to the positive planning model show that the best policy among different options, such as deficit irrigation policy or combined policies, involves implementation of pressurized irrigation systems.  相似文献   

4.
We examine relationships between nationwide sparing use of water and farmer income of China in this article. As increasing implementation of water projects and irrigation system, the cost of water use has increased in many regions. However, as local policy-oriented urban expansion and ecological restoration have carried out during the past decade, water demand has increased. The spatial distributions of water use and farmer income are uneven and their relationships are ambiguous over time, especially it is uncertain that farmers can benefit from those so called water-saving programs when urban expansion grows faster in China. Based on consumption theory, empirical results of Blundell–Bond dynamic panel-data model with generalized method of moments (GMM) estimators indicate saving one percent of water has positive impacts at 0.085–0.35 percent on farmer income in the following statistical year. Population has negative impacts on farmer income. Particularly in Central China, one percent of increase in population will statistically significantly decrease 0.276 percent of contemporaneous farmer income. Particularly, in Eastern China with large population during years 2004 through 2012, the total amount of water use increases one percent, contemporaneous farmer income loses 0.04 percent. Thus, saving water can benefit future farmer income, and it indicates that urban expansion may induce the diversion of resources and agricultural production from rural to urban area. Policy implication of relationships between water allocation and farmer income distribution caused by water-saving programs needs to be further studied at regional scale, in particularly to the regions with large population and urban expansion in China.  相似文献   

5.
目的:分析淋巴结结核的CT和MRI表现特点,并与病理学对照,探讨两种检查方法的应用价值。方法:回顾性分析2010年1月至2014年12月间34例经手术、穿刺病理或临床证实为淋巴结结核患者的CT或MRI影像学资料,分别从生长方式(融合/非融合)、边缘(光滑/欠光滑)、境界(清晰/欠清晰)、密度及信号、增强后强化方式(均匀/不均匀/环形规则/环形不规则)这5个方面对所受累淋巴结进行分析。结果:34例患者中共累及223枚淋巴结,其中颈部淋巴结67.7%,纵隔内淋巴结27.7%,肺门淋巴1.8%,肺内淋巴结0.5%,腹腔淋巴结0.5%,腹膜后淋巴结1.8%。所有受累淋巴结中,8.5%呈融合性生长,83.9%形态规则,79.4%边缘光滑。CT上发现的171枚病变淋巴结以等密度较多(53.8%)、低密度次之(43.3%),MRI上发现的66枚病变淋巴结中98.5%为等T1长T2信号。所有CT及MRI观察到的病变淋巴结中,除57%的病灶密度或信号均匀外,仅伴钙化的为12.6%,仅伴部分坏死的26.9%,另外有3.6%同时伴钙化及坏死;增强扫描的204个病变淋巴结中,1%钙化显著、未见明显强化,38.7%均匀强化,伴坏死者内见不强化的低密度区,11.3%呈环形规则强化(均位于颈部),8.3%环形不规则强化(纵隔内82.4%),5.9%可见病变淋巴结内有分隔样强化(均位于颈部)。结论:CT与MRI对于淋巴结结核具有重要诊断价值,两者均能清晰显示病变部位、形态以及边缘情况,MRI对于病变边缘及周围情况显示较CT更明确,尤其是增强后,对于包膜及邻近组织受累情况的显示也更加敏感。   相似文献   

6.
王洪体  崔仁胜  王宏远  叶鹏  李丽娟 《地震》2020,40(3):153-166
本文在理论上研究了对齐误差对测试地震计自噪声的影响。指出对齐误差影响到2台仪器记录间的计算互功率谱密度, 进而影响到被测仪器记录间相干函数计算, 最终影响到被测仪器的自噪声计算。发现当存在对齐误差时, 在信噪比较高频段计算得到的自噪声水平比仪器的实际自噪声水平要高, 在一般的实际测试中可能高20 dB以上。为了消除对齐误差对自噪声测试的影响, 提出通过投影逆变换把观测记录变换到标准坐标系下, 再用变换后的观测记录来计算地震计自噪声。给出了基于以上思路和传感参数对比测试方法的地震计自噪声计算处理流程, 合成数据、 实际测试数据的处理检验计算结果表明, 本文方法可以有效克服地震计自噪声测试中对齐误差的影响。  相似文献   

7.
运用福建前兆观测台网资料,分析了形变应力场和水位震后效应场等前兆场的空间变化规律与福建区域地震的相关性.结果显示,福建多次ML>4.5地震的孕育过程均伴随着形变应力及水位震后效应的成场.研究认为,当形变应力场与水位震后效应场的时空演化规律趋于一致时,这一区域就具备发生中强以上地震的背景条件,跟踪分析形变应力场及水位震后效应场的空间迁移规律,可对未来发生的地震的空间位置做出较为准确的判断.  相似文献   

8.
The distribution and anomalies of rare earth elements(REEs) of granitic regolith were studied in Inner Mongolia and Hainan Island, China. One profile showed slight REE enrichment of an upper layer and no obvious light REE/heavy REE(LREE/HREE) fractionation(La_N/Yb_N of 0.9). The second profile was significantly enriched in REEs and enriched in LREEs in the upper portion(La_N/Yb_N1.8). Eu, Ce, and Gd anomalies of the two profiles are different. Slightly negative Eu, Ce, and Gd anomalies in NMG-3-1 indicate slow dissolution of primary minerals and little secondary products; in contrast, a positive Eu anomaly in HN-2 suggests the vegetation cycle may contribute to soil. The Ce anomaly of HN-2 reflects oxidation of Ce and coprecipitation by Fe-and Mn-oxides and organic matter. Correlation between Ce and Gd anomalies in HN-2 suggests Ce and Gd are both influenced by redoxreduction.  相似文献   

9.
巢湖沉积物重金属富集特征与人为污染评价   总被引:9,自引:6,他引:9  
本文分析了巢湖主要入湖河流河口区表层沉积物及西部湖心区沉积岩芯中Al、Fe、Ni、Cr、Cu、Zn、Pb、Li、V等金属元素变化特征,采用地球化学方法对金属元素变化的"粒度效应"进行矫正,并以Li、V为参照元素对矫正结果进行检验;参考历史沉积物,对河口区及西部湖心区沉积物重金属人为污染特征进行分析;结合沉积岩芯210Pb年代结果,估算西部湖心区近150a来Ni、Cr、Cu、Zn、Pb等重金属元素的人为污染贡献量.结果表明,河口表层沉积物重金属污染具有显著的空间差异,南淝河河口重金属人为污染最重,其中Ni、Cr、Cu、Zn、Pb的人为污染贡献量分别为12.2、32.2、25.3、479.9和76.0 mg/kg,分别占总含量的35%、37%、64%、92%和77%;其次是柘皋河河口,主要重金属污染元素为Cu、Zn和Pb,人为污染贡献量达57.6、57.0和19.5 mg/kg,分别占总含量的73%、47%和36%;而派河、白石山河、杭埠河等河口表层沉积物中重金属元素人为污染程度较弱.巢湖西部湖心区主要污染元素为Cu、Zn、Pb,人为污染开始于1950s,1980年以来其人为污染贡献量显著增加,平均为16.2、245.6、47.8 mg/(m2.a),分别占各元素沉积通量的23%、61%和37%;Ni人为污染开始于1980s初期,人为污染贡献量平均为12.6 mg/(m2.a),占其沉积通量的13%左右;Cr基本未受人为污染影响.西部湖心区沉积岩芯及南淝河河口表层沉积物中重金属污染程度均表现为Zn>Pb>Cu,而且南淝河河口沉积物重金属污染程度显著高于西部湖心区.结合主要入湖河流径流量与河口沉积物重金属污染特征,认为巢湖西部湖心区重金属污染主要通过南淝河输入,来自合肥等城市的废水是主要的污染源.  相似文献   

10.
浅水湖泊中沉积物碱性磷酸酶动力学参数的分布   总被引:12,自引:3,他引:9  
东湖沉积物磷酸酶在较高的pH范围内表现出较高活性,故为碱性磷酸酶,东湖与严西湖沉积物中碱性磷酸酶的动力学参数表现出明显的空间异质性,且与间隙水和表层水中正磷酸根浓度无明显的对应关系,此外,它们在垂直方向上亦极具变化,除在沉积物表面显示较高催化效率之外,较沉层面(约距表面8-12cm)亦有类似峰值,这一结果补充说明了湖泊沉积物磷循环的另一活跃区域以及相应的生物化学机制。  相似文献   

11.
An electric furnace with oxygen-fugacity control was constructed. Oxygen partial pressure inside the furnace is controlled by flowing H2 and CO2 gas mixtures in different ratios. The system is set up inside a three-layer permalloy shield and a solenoid coil to produce an axial magnetic field. Oxygen fugacities are directly measured by an yttriadoped zirconia probe. The difference between the predicted and measured values of fugacities was small at 1,200°C, but a substantial discrepancy was observed at 780°C. Thermoremanent magnetization (TRM) was produced in various gas mixtures by heating the samples of recent basaltic lavas of Oshima (Japan) and Hawaii to 600 or 800°C for 1 h and cooling in a 0.4-Oe field. In general, the TRM is larger when produced in an oxidizing atmosphere and smaller in a reducing atmosphere. Alternating field demagnetization shows that the coercivity is also increased (decreased) when the TRM is acquired in oxidizing (reducing) conditions. However, these properties depend also on the previous heat treatments of the samples.  相似文献   

12.
裂隙岩体渗透性空间分布的指示克里格估值   总被引:2,自引:2,他引:2       下载免费PDF全文
本文较详细介绍了指示克立格估值的基本方法和原理,以指示变异函数为基本工具分析了向家坝坝址区裂隙岩体渗透性空间分布的结构特征,表明该址区裂隙岩体渗透性存在明显的各向异性特征;在此基础上用指示克立格法对未采样点处进行估值,估值结果显示坝址区裂隙岩体渗透性存在明显的壳状渗透结构特征.通过这一实际应用,表明指示克立格法可以较好地描述裂隙岩体渗透性的空间分布规律.  相似文献   

13.
Measurements have been made on specimens in which grains of magnetite of diameter 200 μm were dispersed and immobilized. The results obtained for magnetization and demagnetization by isothermal, anhysteretic and heating procedures are given, and discussed in terms of a model which assumes that the grains comprise a central core of magnetic domains separated by 180° domain walls enclosed in a thin surface layer comprised of pseudo single-domain-like domains.  相似文献   

14.
Aquifers of the peninsulas of Florida and northern Yucatan are Tertiary marine carbonate formations showing many lithologic and faunal similarities. In addition, the tropical to subtropical climates of the two areas are similar, each having annual rainfall of about 1000 to 1500 mm.

Despite similarities in these fundamental controls, contrasts in the hydrologic and geochemical systems are numerous and striking. For example, Florida has many rivers; Yucatan has none. Maximum thickness of fresh ground water in Florida is about 700 meters; in the Yucatan it is less than 70 meters. In Florida the gradient of the potentiometric surface averages about 1 meter per kilometer; in the Yucatan it is exceedingly low, averaging about 0.02 meter per kilometer. In Florida the chemical character of water changes systematically downgradient, owing to solution of minerals of the aquifer and corresponding increases in total dissolved solids, sulfate, calcium, and Mg-Ca ratio; in the Yucatan no downgradient change exists, and dominant processes controlling the chemical character of the water are solution of minerals and simple mixing of the fresh water and the body of salt water that underlies the peninsula at shallow depth.

Hydrologic and chemical differences are caused in part by the lower altitude of the Yucatan plain. More important, however, these differences are due to the lack of an upper confining bed in Yucatan that is hydrologically equivalent to the Hawthorn Formation of Florida. The Hawthorn cover prevents recharge and confines the artesian water except where it is punctured by sinkholes, but sands and other unconsolidated sediments fill sinkholes and cavities and impede circulation. In the Yucatan the permeability of the entire section is so enormous that rainfall immediately infiltrates to the water table and then moves laterally to discharge areas along the coasts.  相似文献   


15.
现代公共建筑非结构构件的投资比远远大于结构构件的建造成本比例,非结构构件在地震中的破坏会造成巨大经济损失。作为一种典型的非结构构件,管线系统的破坏往往导致建筑丧失给水、排水以及消防等多重使用功能。从拟静力试验、动力试验、振动台试验、数值模拟及易损性分析等角度对管线系统抗震性能研究方法进行了系统总结,介绍各类研究方法的应用实例及其利弊,并对管线系统抗震性能研究方法的发展方向进行了展望。  相似文献   

16.
The strongly deformed eclogites are well developed in ultra-high pressure jadeite-quartzite zone of the Dabie Mountains, Eastern China, and garnets had been deformed strongly. Observations by transmission electron microscopy identified not only structure of plastic deformation occurring as free dislocation, dislocation loops and dislocation walls, but also clusters of water molecules present in the deformed garnet. Using infrared spectroscopy, two types of hydrous components are identified as the hydroxyl and free-water in the garnet. Based on analysis of microstructure mechanism of deformation in garnets, and experimental data of petrology, the clusters of water molecules were considered to lead strong plastic deformation of garnet by dislocations because of mechanical weakening.  相似文献   

17.
本文目的在于评价先天性胆管囊肿影像学诊断的价值及首选检查方法。所用的材料与方法是搜集68例术前经腹部平片、胃肠钡餐检查、静脉胆道造影、ERCP、PTC、B超、CT检查并经手术证实的病例行回顾性分析。结果是B超简单,可重复检查,阳性率74.6%;CT能清晰显示胆管囊肿的部位,大小,类型。对Carolis病有特别价值,ERCP检查痛苦,对小儿不适宜;PTC为创伤性检查,静脉胆道造影显示病变不隹;腹部平片,胃肠钡餐造影仅能显示病变间接征象。结论得出:对胆管囊肿的检查诊断,首选CT和B超,ERCP和PTC,应该做为补充检查方法  相似文献   

18.
为厘清张北地区农村房屋抗震性能现状,对受张北地震影响最为严重的张北和尚义2县的农村房屋进行抽样调查,结合已有农村房屋震害经验,利用综合分析方法,建立该地区农村房屋抗震性能指数,并对其抗震性能进行定量分析。结果显示,该地区农村现有房屋以砖木结构和土木结构为主,抗震性能普遍较差;针对该地区农村房屋现状,给出改进其抗震性能的建议,对该地区地震风险管理具有一定的借鉴意义。  相似文献   

19.
The general features of the region of interaction of the solar wind with the ionosphere of Venus and Mars are compared using data obtained with the Mariner 5 and the Pioneer Venus Orbiter (PVO) spacecraft for Venus and with the Phobos II, the Mars Global Surveyor (MGS) and the Mars Express spacecraft for Mars. Despite the overall weak intrinsic global magnetic field that is present in both planets there are significant differences in the manner in which the interplanetary magnetic field accumulates and is organized around and within their ionosphere. Such differences are unrelated to the crustal magnetic field remnants inferred from the MGS measurements around Mars. In fact, while in Venus and Mars there is a region in which the magnetic field becomes enhanced as it piles up in their plasma environment it is shown that such a region exhibits different regimes with respect to changes in the ion composition measured outside and within the ionosphere. At Venus the region of enhanced magnetic field intensity occurs in general above the ionopause which represents the boundary across which there is a change in the ion composition with dominant solar wind protons above and planetary O+ ions below. At Mars the region of enhanced magnetic field is located below a magnetic pileup boundary across which there is also a comparable change in the ion composition (solar wind protons above and planetary O+ ions below). It is argued that this difference in the relative position of the region of enhanced magnetic field with respect to that of a plasma boundary that separates different ion populations results from the peculiar response of the ionosphere of each planet to the oncoming solar wind dynamic pressure. While at Venus the peak ionospheric thermal pressure is in general sufficient to withhold the incident solar wind kinetic pressure there is a different response in Mars where the peak ionospheric thermal pressure is in general not large enough to deviate the solar wind. In this latter case the ionosphere is unable to force the solar wind to move around the ionosphere and as a result the oncoming electron population can reach low altitudes where it is influenced by neutral atmospheric particles (the solar wind proton population is replaced at the magnetic pileup boundary which marks the upper extent of the region where the interplanetary magnetic field becomes enhanced). Peculiar conditions are expected near the magnetic polar regions and over the terminator plane where the solar wind is directed along the sides of the planet.  相似文献   

20.
江娃利  张英礼 《中国地震》1997,13(3):263-270
讨论了华北平原周边1975年海城地震,1937年荷泽地震及1830年磁县地震3次强震的地表地震破裂特征以及这3个地区北西向断裂的全新世活动。研究结果表明,尽管这3次强震地表破裂显示较弱,断续分布,仍反映了存在北西向地表破裂带,活动方式呈左旋走滑兼正倾滑。  相似文献   

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